SusChEM: Controls on struvite neogenesis and reactivity in engineered and geochemical systems

磷(P)可作为一种矿物鸟粪石(镁NH4PO4·6H2O)从人类和农业废弃物中回收，可作为传统肥料的替代品。该项目探讨了鸟粪石在从不同类型的废物中产生时的性质和反应性，并与通过化学方法产生的鸟粪石进行了比较。这项研究的目的是阐明决定鸟粪石物理和化学性质的主要条件和参数，而不依赖于新生来源。鸟粪石将从猪排泄物、温室废水和莫诺湖水中沉淀出来。动植物废弃物是鸟粪石回收工程系统中常用的废弃物，莫诺湖是一个历史上曾发生过鸟粪石的地球化学系统。以去离子水为溶剂的模型溶液将被用来确定对所生成的矿物性质的具体控制；即pH、离子强度、溶解有机物。还将评估起始溶液中普遍存在的金属等痕量污染物的吸附情况。这一点尤其关键，因为鸟粪石的性质对吸附过程的影响以前还没有确定，相反地，吸附的杂质对矿物结构和稳定性的影响是未知的。这项研究将实施几项先进和创新的技术，包括P XAFS、31P核磁共振、33P放射性示踪剂和TG/DSC-FT-IR，这些技术可移植到其他磷矿的研究中。这项研究的结果可以用来操纵工程系统中鸟粪石的性质，这取决于废物的成分和实施条件。从废物中更好地设计鸟粪石的能力将促进鸟粪肥的使用，并鼓励可持续使用磷对社会的重要性人类磷(P)循环是不可持续的。这是因为磷是一种有限的自然资源，人类活动加速了磷的循环，因为它被用作肥料。随着地质磷储量的减少和全球人口的不断增加，人类周期中损失的磷需要弥补。这可以通过从人类和农业废弃物中回收磷作为磷酸盐矿物鸟粪石来实现。利用回收的鸟粪石作为替代肥料，将促进磷的可持续利用，保护自然磷资源，并限制岩石中储存的额外磷的释放进入人类周期。该项目将使人们更好地了解鸟粪石从各种来源，包括动物和植物废物中产生时的物理和化学性质。根据废水成分和回收条件，结果可用于预测和潜在地控制回收鸟粪石的性质和污染物含量。这确保了作为肥料输送到土壤中的鸟粪石可以按要求发挥作用，不会造成污染风险，从而对土壤、农业生态系统和地球化学系统造成环境责任。最终，再利用从废物中回收的鸟粪石作为磷的来源，将通过提供一种替代的、可持续的肥料来养活日益增长的全球人口，从而为人类的磷循环带来可持续性。

Technical DescriptionPhosphorus (P) can be recovered from human and agricultural wastes as the mineral struvite (MgNH4PO4·6H2O), which can be used as an alternative to traditional fertilizers. This project addresses the properties and reactivity of struvite when generated from different types of wastes, and as compared to geochemically produced struvite. The goal of the research is to elucidate the overarching conditions and parameters that dictate the physical and chemical properties of struvite, independent of source of neogenesis. Struvite will be precipitated from swine effluent, greenhouse wastewater, and Mono Lake water. The animal and plant wastes are commonly used in engineered systems for struvite recovery, and Mono Lake is a geochemical system with a historical occurrence of struvite. Model solutions, with deionized water as the solvent, will be used to determine the specific controls; i.e. pH, ionic strength, dissolved organics; on the resultant mineral properties. The sorption of trace contaminants such as metals, prevalent in starting solutions, will also be assessed. This is particularly critical because the impact of struvite properties on sorption processes has not been previously determined, and conversely the effect of sorbed impurities on the mineral structure and stability are not known. The research will implement several advanced and innovative techniques, including P XAFS, 31P NMR, 33P radiotracers and TG/DSC-FT-IR, which are transferable to the study of other phosphate minerals. Results from this research can be used to manipulate the properties of struvite in engineered systems, contingent upon waste composition and implemented conditions. The ability to better engineer struvite from wastes will advance the use of struvite fertilizers and encourage the sustainable use of P.Importance for SocietyThe human phosphorus (P) cycle is unsustainable. This is because P is a limited natural resource, the cycling of which is accelerated by human activity due to its use as fertilizer. With diminishing geologic P reserves, and an ever increasing global population, P lost in the human cycle needs to be recouped. This can be achieved by the recovery of P from human and agricultural wastes as the phosphate mineral struvite. The use of recovered struvite as an alternative fertilizer source will promote the sustainable use of P, conserve natural P resources, and limit the release of additional P sequestered in rocks to the human cycle. This project will provide an improved understanding of the physical and chemical properties of struvite when generated from a variety of sources, including animal and plant wastes. Results can be used to predict, and potentially control, the properties and contaminant content of recovered struvite based on wastewater composition and recovery conditions. This provides the security that struvite delivered to soils as fertilizer can function as required and does not pose a contamination risk, and thus an environmental liability to soils, agro-ecosystems and geochemical systems. Ultimately, the reuse of struvite recovered from wastes as a source of P will introduce sustainability to the human P cycle by providing an alternative, sustainable fertilizer to feed a growing global population.